Current limiting circuit breaker with improved auxiliary toggle mechanism



Jan. 5, 1965 A. BoDENscHATz 3,164,700

CURRENT LIMITING CIRCUIT BREAKER WITH IMPROVED AUXILIARY TOGGLE MECHANISM INVENTOR. m/fwr aaai/wwwa Jan. 5, 1965 A. BoDENscHATz 3,164,700

CURRENT LIMITING CIRCUIT BREAKER WITH IMPROVED AUXILIARY TOGGLE MECHANISM Filed April 13, 1959 2 Sheets-Sheet 2 United States Patent Oiice 3,164,700 Patented Jan. 5, 1965 3,164,760 CURRENT LUi/liTiNG CWQCUH EREAKER WTCH lirilil'lVED AUXELEARY 'il MECliiiAsllSlt/i August Bodenschatz, Philadelphia, Pa., assigner to l-'BE ireuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Filed i3, 1959, tier. No. iiledlfil il Clahns. (Cl. Zilli-116) This invention is directed to a current limiting circuit breaker which does not utilize an auxiliary current limiting means, such as a fuse, wherein initial high speed contact separation for imparting the current limiting characteristic to the unit need not continuously operate against contact closing pressure.

Current limiting circuit breakers have been disclosed in copending application, Serial No. 770,321, led Oct. 29, 1958, in the name of William Harold Edmunds, and entitled Current Limiting Circuit Breaker now issued as US. Patent 3,012,118. ln the above noted application, the unusual action of a current limiting nature due to an initial and high speed contact separation prior to operation of the contact operating mechanism has been fully discussed.

Generally, the principle of the current limiting circuit breaker is to cause an initial high speed opening of the contacts independently of the operating mechanism and before the motion of the operating mechanism can be initiated. rIherefore, the contact closing bias from the main operating mechanism operates on the movable contact, and the initial contact opening means must work against this bias.

This bias is normally derived from some type of spring means wherein the force which biases the Contact closed increases as the movable contact is moved toward a disengaged position. Therefore, a substantial amount of energy will be required of the solenoid or blow-open circuit, or similar circuit, causing the initial contact opening independently of the operating mechanism.

The principle of this invention is to provide a novel contact mechanism wherein the required contact pressure bias is provided, but this contact pressure bias may be quickly overcome after an initial application of force and independently of the main operating mechanism of the circuit breaker.

ln the preferred embodiment of the present invention, the normal circuit breaker operating mechanism is connected to the movable contact through an auxiliary toggle mechanism. When the toggle is in its latched or overcenter position, the toggle spring urges the movable contact closed through its toggle mechanism. When, however, there is an initial force applied to the movable contact due to the auxiliary means which is to cause the initial separation of the contacts independently of the main operating mechanism, the initial force need only throw the auxiliary toggle over-center whereby it will snap to a collapsed position. Thus, the initial contact opening motion will be provided after only a relatively slight amount of energy is derived from the auxiliary operating mechanism.

The complete auxiliary toggle is carried by a frame in a preferred embodiment. The frame is then connected to and moved by the main operating mechanism between the contact engaged position and the contact disengaged position when manual operation of the unit or operation by the main operating mechanism is required.

Accordingly, the primary object of my invention is to provide a novel current limiting circuit breaker wherein initial contact motion is easily obtained independently of the circuit breaker operating mechanism.

Another object of my invention is to provide a novel structure for delivering a substantial contact closing pressure which may be overcome by the application of a given force for a relatively short time.

Another object of my invention is to provide a novel contact pressure means for circuit breakers which can be overcome by a relatively small amount of energy.

A further object of my invention is to provide a novel contact pressure biasing means for current limiting circuit breakers which may be operated by auxiliary operating means for effecting high speed initial contact separation without requiring a substantial amount of energy from the auxiliary mechanism.

These and other objects of my invention will now become apparent from the following description when taken in connection with the drawings, in which:

FIGURE l shows a side cross-sectional View of a typical circuit breaker adapted in accordance with my novel auxiliary operating mechanism.

FIGURE 2 is a perspective view of the frame for supporting my novel auxiliary operating mechanism.

FGURE 3 is a perspective view of the toggle which forms my novel operating mechanism and is attached to the movable contact where the toggle is in its over-center position.

FGURE 4 illustrates the toggle of FIGURE 3 when in the collapsed position.

FlGURE 5 is a perspective view of the manner in which the frame of FIGURE 2 supports the toggle of FlGURES 3 and 4, and further illustrates the manner in which the main operating mechanism crank is connected to the frame.

FIGURE 6 illustrates a side cross-sectional view of the auxiliary operating mechanism with the contacts in their closed position and the toggle in its over-center position.

FIGURE 7 is similar to FIGUREy 6, and illustrates the toggle in its collapsed position as due to a short circuit carried by the breaker and prior to the time at which the normal operating mechanism operates.

FiGURE 8 is similar to FlGURES 6 and 7, and illustrates the manner in which the Contact is moved to a disengaged position through the main operating mechanism which moves the frame of the auxiliary operating mechanism.

Referring first to FIGURE l, a typical circuit breaker is shown therein which comprises a molded housing 10 having an operating handle l2 connected thereto. The circuit breaker shown has a line terminal 14 and a load terminal i6 which are interconnected by a conductive member i3 which carries stationary contact 20, movable Contact 22, pigtail 24 connected to movable Contact 22, the trip unit 215, and pitail 28 which is connected from trip unit 26 to terminal 16. Contacts 20 and 22 are associated with an arc chute 29 in the usual manner.

The trip unit 26 has been illustrated herein as a block, and the details of its construction have been omitted. It will be obvious that trip unit 26 may be of any desired standard type having overload elements or instantaneous trip devices. It is suiiicient for purposes of the present invention to understand that the trip unit operates to remove a latch 3@ from cradle 32 which is pivotally mounted at xed pivot 34 when trip unit 26 is actuated by predetermined fault condition.

The circuit breaker operating mechanism includes the aforementioned cradle 32 and a .toggle mechanism formed of toggle links 3e, 3S which drive bell crank 4Q. The bell crank 4i@ and toggle link .3S may be seen in FIGURE 5 as double members. Toggle link 35 is pivotally carried on a central portion of cradle 32 by pin rei-2, and toggle links 36 and 3S are joined by pivot pin 44. The lower toggle link 33 is then pivotally connected to one end of bell crank iti by a pivot pin and the bell crank 4t) is pivotally mounted on iixed pivot 4S. The main toggle spring 59 for operating the aforementioned main toggle n, :3 mechanism is then connected between a portion of operating handie l2 and the knee of the toggle or pin 44.

In operation, it is clear that so long as latch 3@ is latched, movement of operating handle I2 to the right will cause spring Sii to move to the right of pin 42 and thus snap the lmee of the toggle or pin de to the right. This will cause a rotation of bell crank 4@ in a counterclockwise direct-ion about its pivot 4S to cause a subsequent contact opening operation, as will be described more fully hereinafter. In a like manner, the toggle can be snapped back to the position shown, the Contact engaged position, by moving spring Sti to the lett of a line joining pin 42 and pin 44.

In the event that the trip unit is operated and latch 30 is removed, the cradle 32 willrotate in a counterclockwise direction under the influence of spring 5d until pivot pin 42 passes to the left of spring 56, at which point the toggle will again collapse to the right to cause the subsequent contact openingT operation.

The essence of the present invention is to provide a novel auxiliary operating mechanism which may operate the contacts to a disengaged position independently of the aforementioned main operating mechanism in a very high speed manner so as to impart a current limiting characteristic to the interrupter. T his operating mechanism structure may be best understood from FIGURES 2 through 5 which show a trame and an auxiliary toggle mechanism associated with movable contact 22.

More specifically, the movable contact 22 is carried by a rod 52 which has a magnetically responsive portion Se at the end thereof which is positioned to move into solenoid S6. Note that rod 52 could be made of steel and in a single piece. The contact rod 52 extends through apertures 5S and 60 of frame 62, as best seen in FIGURE .2. As then shown in FIGURES 3, 4, and 5, a central portion of rod S2 receives a pin 64 which rides in a pair of slots 66 on either side of frame 62. Pin 64 further serves as the knee of an auxiliary toggle formed by pairs of toggle links 6d-7i), and 72374 respectively. The upper end of the toggle is completed by pin 76 which receives the upper ends of links 63 and 7d where pin 76 is carried in opposing slots 7S and Sd of frame 62, as seen best in FIGURE 5, while the lower end of the toggle is completed by pin 52 which receives the lower end of links 72 and 74 and rides in opposing slots 34 and S6 of frame 62, as seen in FIGURE 5. The upper and lower toggle pins 76 and 82 respectively are then connected by toggle springs S3 and 9*@ which lie on the outside o the frame 62, as seen in FIGURE 5.

The auxiliary toggle mechanism is shown in FIGURE 3 where the toggle is in its over-center position, this being the position of FIGURE 5. As illustrated in FIGURE 4, however, the toggle can collapse to the right after being moved past its over-center position, whereupon contact rod 52 is moved backwardly with respect to frame 62 with toggle knee pin 64 riding in slot 66.

The final position of the collapsed toggle may obviously be determined, either by the depth of slots 78, 8), 84 and 32 of frame 62, or by the length of slot 66 of frame 62. y

The frame 62 is movably mounted within the circuit breaker in any desired manner. For example, a pair of angle supports, such as angle support 92 of FIGURE l, may be provided with a slot 94 which receives inward projections on either side of trame 62, such as inward projections 96 and 98 for the side shown in FIGURE 2. The slot 94 is made long enough to carry inward projections 96 and 9S throughout the complete required length of travel of frame 62 when this member is moved by the circuit breakermain operating mechanism with the maximum travel of rod 52 being determined by stop 99.

In order to carry contact rod 52 with frame 62 when the frame is moved, rod 52 is provided with an adjustable collar I0@ which receives the inner face adjacent aperture 5S of frame 62, when frame 62 is moved to the right in the figures. There is, however, a small distance between these two members when the circuit breaker is in its closed position so that toggle springs 8S and 9i) or the auxiliary operating mechanism may exert the required contact pressure.

As previously described, the frame 62 is driven by the main operating mechanism through the pivotally mounted bell crank dit. This construction is best seen in FIGURES 1 and 5 where the lower end of bell crank in is provided with slots, such as slot 202, which receive projections on opposing sides of frame 62, such as projections iii-4i and litio of FIGURE 5.

Accordingly, as bell crank it? is rotated under the iniuence of the main toggle mechanism, projections 104 and will ride within the bell crank slots, such as slot 162, as frame 62 is driven along its longitudinal guide slot 9d, as above described.

In order that contact 22 may be quickly moved toward a disengaged position responsive to the occurrence of predetermined fault conditions, the contact rod 52 may be initially moved by either the blow-oit force on the Contact, or by the auxiliary solenoid 56, or by both, independently of the main operating mechanism. Thus, conductor i8 of FIGURE l, contacts 2t? and 22 and pigtail 24 form a U-shaped current path which, under the iniiuence ot predetermined fault currents such as very rapidly rising fault curents, will effect a blow-off force tending to drive Contact 22 to the right.

Furthermore, solenoid 56 may be provided with an energizing circuit schematically illustrated by block M3 which is associtaed in some manner with pigtail 24, `as illustrated by the dotted lines, or with one of the other portions ot the circuit breaker which will conduct a predetermined fault current. As was the case with the blowoff circuit, when the fault current `is of some predetermined nature which may be beyond the interrpting ability of the trip unit 26, solenoid 56 will be energized to attract magnetic portion 5d of rod 52 and cause a rapid motion of movable contact 22 to the right substantially prior to the time that the operation of trip unit 26 will cause operation of the main operating mechanism so as to impart the desired current limiting character to the breaker.

One of the main advantages of my novel operating mechanism is that a relatively small amount of energy is required of the auxiliary operating means which is to initially move the movable contact to a disengaged position. This operation is best understoood from FIG- URES 6, 7 and 8.

Referring first to FIGURE '6 which shows an enlarged view of the auxiliary operating mechanism and contacts of FIGURE l, it is clear that frame 62 will be held in a` position determined by the main operating mechanism so that the over-center toggle formed of links 7@ and 745 will tend to drive the knee formed by pin 64 to the left, to cause a substantial contact engaging pressure between movable contact 22 and stationary contact 20. When, however, a force is applied to contact rod 52, as due to the blow-oit action of the contact, or the energization of solenoid 56, or both, the contact moves to the right against the force of toggle spring @il (as well as spring $3 on the other side of the frame 62) to extend these toggle springs only until knee pin 64 moves to the right of the line joining upper pin 76 and lower pin 32. At this point, the toggle is broken and the contact 22 will very rapidly continue to move to the disengaged position of FIGURE 7 as the toggle collapses to the position of FIGURE 7.

Thus, the only energy required of the auxiiiary mechanism is the energy needed to `'drive the auxiliary toggles over-center, as contrasted to requiring a power for continuously operating against a continuous bias such as toggle spring Sil which continually exerts a contact closing force until the main operating mechanism operates.

Once the position of FIGURE 7 is reached, the main operating mechanism, which was released through its trip unit 26 of FIGURE l by the same fault that actuated the initial contact motion of rod 52, catches-up to rod 52, and continues to move the rod 52 through frame 62 to the fully disengaged position of FIGURE S.

It will be noted that the frame 62 continues to move after rod 52 engages stop 99. This permits the auxiliary toggle links lil and '74 to be reset since the center pin 64 is stopped, but upper pins 76 and 82 are still moved to the right. Since the resetting operation is automatic, it is only necessary to reset the main operating mechanism by resetting cradle 32 by means not shown but well known to the art, and the breaker can be reclosed to the position of FIGURE 6. When this reclosing occurs, collar 100 and rod 52 will move with respect to frame 62 from its engaging position of FIGURE 8 to the spaced position of FIGURE 6 to permit the toggle spring 90 to supply the required contact engaging pressure between contacts 20 and 22.

Although I have described preferred embodiments of my novel invention, many variations and modifications will now be obvious to those skilled in the art, and I prefer therefore to be limited not by the specilic disclosure herein but only by the appended claims.

I claim:

1. A current limiting circuit breaker; said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and disengaged position with respect to one another, a main operating mechanism operatively connected to at least one of said pair of cooperating contacts and an auxiliary operating means operatively connected independently of said main operating mechanism to said one of Asaid pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; biasing means for said one of said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in` their said engaged position; said auxiliary operating means being operatively connected to said biasing means; a frame; said frame being connected to said main operating mechanism; said one of said pair of cooperable contacts being carried by said frame; said frame further carrying toggle means; one portion of said toggle means being connected to said one of said pair of cooperating contacts, another portion of said toggle being connected to said frame; said toggle means biasing said one of said pair of cooperating contacts into engagement with theother of said pair of cooperating contacts; said one of said pair of cooperating contacts being movable with respect to said frame to a toggle collapse position to quickly remove said bias of said toggle means.

2. A current limiting circuit breaker; said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and disengaged position with respect to one another, a main operating mechanism operatively connected to at least one of said pair of cooperating contacts and an auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair'of cooperating contacts before said main operating mechanism operates; biasing means for said one ol said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in their said engaged position; said auxiliary operating means being operatively connected to said biasing means; a frame; said frame being connected to said main operating mechanism; said one of said pair of cooperable contacts being carried by said frame; said frame further carrying toggle means; one portion of said toggle means being connected to said one of said pair of cooperating contacts, another portion of said toggle being k connected to said frame; said toggle means biasing said one of said pair of cooperating contacts into engagement with the other of said pair of cooperating contacts; said one of said pair of cooperating contacts being movable with respect to said frame to a toggle collapse position to quickly remove said bias of said toggle means; said one of said contacts being initially moved with respect to said frame by said auxiliary operating mechanism.

3. A current limiting circuit breaker; said current limiting circuit breaker comprising a relatively stationary contact, a relatively movable contact movable into and out of engagement with said relatively stationary contact, a main operating mechanism operatively connected to said relatively movable contact, a manual operating means operatively connected to said main operating mechanism for manually operating said movable contact, a trip means operatively connected to said main operating mec-hanism for automatically operating said movable contact, a movable contact biasing means, and an auxiliary operating mechanism; said biasing means being operativelyy connected to said movable contact for biasing said movable contact into engagement with said stationary contact when said movable contact is in engagement with said stationary contact; said auxiliary operating mechanism being operatively connected to said movable contact independently of sai-d main operating mechanism and moving said movable contact toward a disengaged position independently ot said main operating mechanism responsive to predetermined conditions; a frame; said frame being connected to said main operating mechanism and movable thereby; said movable contact being carried by said frame and movable with respect thereto; said frame having one portion or" a toggle spring means connected thereto to serve as said biasing means; said movable contact being connected to another portion of said toggle springs means; said toggle spring means being collapsed when said movable contact is moved toward a disengaged position by said auxiliary operating mechanism with respect to said frame.

4. A contact pressure means for a first contact movable into and out of engagement with respect to a second contact; said contact pressure means including a frame, and a toggle means; said first contact being carried by and being movable with respect to said frame; said frame being movable between a Contact engaged and a contact disengaged position; said toggle means having a first portion connected to said frame and a second portion connected to said movable contact; said toggle means biasing said movable contact into high pressure contact engagement with said second contact when said iirst and second contacts are engaged; said movable Contact moving Said toggle to an overcenter position when said movable contact is moved toward a disengaged position and said frame is maintained relatively stationary to defeat the bias of said toggle means.

5. A current limiting circuit breaker; said current limitiney circuit'breaker including a pair of cooperating contacts movabley between an engaged and disengaged position with respect to one another, a main operating mechanism having a iirst toggle means operatively connected to at least one or said pair of cooperating contacts and an auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; biasing means for said one of said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in their said engaged position; said auxiliary operating means being operatively connected to said biasing means; said auxiliary operating means defeating said biasing means after initially disengaging said pair of cooperating contacts, said biasing means including a second toggle and a spring; said second toggle having outer ends operatively connected to said main operating mechanism, and having said outer ends connected to each other by said spring; said second toggle having a knee operatively connected to and movable with said one of said cooperating contacts; said second toggle being operative independently of said main operating mechanism and operative to aid said auxiliary operating means after a predetermined movement thereof; said auxiliary operating means comprised of a U-shaped con-ductive path including said cooperating contacts operatively positioned to move said one of said pair of cooperating contacts in an axial direction when said predetermined fault condi-tion occurs.

6. A current limiting circuit breaker; said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and disengaged position with respect toi one another, a main operating mechanism having a iirst toggle means operatively connected to at least one of said pair of cooperating contacts and an auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; biasing means for said one of said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in their said engaged position; said auxiliary operating means being operatively connected to said biasing means; said auxiliary operating means defeating said biasing means after initially disengaging said pair of cooperating contacts, said biasing means including a second toggle and a spring; said second toggle having outer ends operatively connected to said main operating mechanism, and having said outer ends connected to each other by said spring; said second toggle having a knee operatively connected to and movable with said one of said cooperating contacts; said auxiliary means comprised of a conducto-1 operatively positioned to move said one of said pair of cooperating contacts in an axial direction when said predetermined fault condition occurs; said movement thereby moving said second toggle -to an overcenter position to thereby permit said toggle to aid said movement; said second toggle being operative independently of said main operating mechanism and operative to aid said auxiliary operating means after a predetermined movement thereof.

7. A current limiting circuit breaker; said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and disengaged position with respect to one another, a main operating mechanism having a first toggle means operatively connected to at least one of said pair of cooperating contacts and an auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; biasing means for said one of said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in their said engaged position; said auxiliary operating means being operatively connected to said biasing means; said auxiliary operating means defeating said biasing means after initially disengaging said pair of cooperating contacts, said biasing means including a second toggle and a spring; said second toggle having outer' ends operatively connected to said main operating mechanism, and having said outer ends connected to eac-h other by said spring; said second toggle having a knee operatively connected to and movable with said one of said cooperating contacts; said second toggle being operative independently of said main operating mechanism and operative to aid said auxiliary operating means after a predetermined movement thereof; said auxiliary operating means comprised of a conductor and a solenoid; said conductor and solenoid operatively positioned to move said one of said pair of cooperating contacts in an axial direction when said predetermined fault condition occurs.

8. A current limiting circuit breaker; said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and disengaged position with respect to one another, a main operating mechanism having a first toggle means operatively connected to lat least one of said pair of cooperating contacts and a-n auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair of cooperating contacts; said auxiliary operating means being operable responsive to predetermined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; biasing means for said one of said pair of cooperating contacts for biasing said pair of cooperating contacts into engagement when said cooperating contacts are in their said engaged position; said auxiliary operating means being operatively connected to said biasing means; said auxiliary operating means defeating said biasing means after initially disengaging said pair of cooperatng contacts, said biasing means including a second toggle and a spring; said second toggle having outer ends operatively connected tosaid main operating mechanism, and having said outer ends connected to each other by said spring; said second toggle having a knee operatively connected to and movable with said one of said cooperating contacts; said auxiliary operating means comprised of a conductor and a solenoid; said conductor and solenoid operatively positioned to move said one of said pair of cooperating contacts in an axial direction when said predetermined fault condition occurs; said movement thereby moving said second toggle to an overcenter position enabling said second toggle to aid said movement; said second toggle being operative independently of said main operating mechanism and operative to aid said auxiliary operating means after a predetermined movement thereof.

9. A contact pressure means for a iirst contact movable into and out of engagement with respect to a second contact; said contact pressure means including a frame, and a toggle means; said first contact being carried by and being movable with respect to said frame; said frame being movable between a contact engaged and a contact disengaged position; said toggle means having a first portion connected to said frame and a second portion connected to said movable contact; said toggle means biasing said movable contact into high pressure contact engagement with said second contact when said first and second contacts are engaged; said movable contact moving said toggle to an overcenter position when said movable contact is moved toward a disengaged position and said frame is maintained relatively stationary to defeat the bias of said toggle means; said movable contact being movable toan axial direction with respect to said frame.

10. A contact pressure means for a first contact movable into and out of engagement With respect to a second contact; said contact pressure means including a frame, and a toggle means; said first contact being carried by and being movable with respect .to said frame; said frame being movable between a contact engaged and a contact disengaged position; said toggle means having a first portion connected to said frame and a second portion connected to said movable contact; said toggle means having a -iirst and second position; said toggle means biasing said movable contact into high pressure contact engagement with said second contact when said first and second contacts are engaged; said movable contact moving said toggle to said second position when said movable contact is moved toward a disengaged position and said frame is maintained relatively stationary to defeat the bias of said toggle means; said frame being movable with respect to said movable contact after disengagement of said tirst and second contacts to automaticaily return said toggle means to said first position.

11.A current limiting circuit breaker, said current limiting circuit breaker including a pair of cooperating contacts movable between an engaged and a disengaged position with respect to one another, a main operating mechanism, biasing means operatively connected between said main operating mechanism including a first toggle means movable to a irst position for moving said cooperating contacts -towards an engaged position; said biasing means including a second toggle means and a spring; said second toggle having outer ends operatively connected to said main operating mechanism, and having said -outer ends connected to each other by said spring; said second toggle having a knee operatively connected to one of said pair of cooperating contacts; said biasing means being adapted to urge said cooperating contacts into irin engagement when said main operating mechanisrn is in said first position, auxiliary operating means operatively connected independently of said main operating mechanism to said one of said pair 'of cooperating contacts; said auxiliary operating means being operable responsive to pre-determined fault conditions to initiate opening of said pair of cooperating contacts before said main operating mechanism operates; said auxiliary operat- Reierences Cited by the Examiner UNITED STATES PATENTS*V r 2,516,027 7/50 Stuellein et al. 200-88 2,824,922 2/58 Jennings 20G-88 2,863,964 12/58 Taylor et al. 200-88 2,892,054 6/59 Walker et al 200-88 3,012,118 12/61 Edmunds 200-88 FOREIGN PATENTS 165,563 7/21 Great Britain.

347,007 4/ 31 Great Britain.

893,020 1/44 France.

BERNARD A. GILHEANY, Primary Examiner.

RICHARD M. WOOD, Examiner. 

11. A CURRENT LIMITING CIRCUIT BREAKER, SAID CURRENT LIMITING CIRCUIT BREAKER INCLUDING A PAIR OF COOPERATING CONTACTS MOVABLE BETWEEN AN ENGAGED AND A DISENGAGED POSITION WITH RESPECT TO ONE ANOTHER, A MAIN OPERATING MECHANISM, BIASING MEANS OPERATIVELY CONNECTED BETWEEN SAID MAIN OPERATING MECHANISM INCLUDING A FIRST TOGGLE MEANS MOVABLE TO A FIRST POSITION FOR MOVING SAID COOPERATING CONTACTS TOWARDS AN ENGAGED POSITION; SAID BIASING MEANS INCLUDING A SECOND TOGGLE MEANS AND A SPRING; SAID SECOND TOGGLE HAVING OUTER ENDS OPERATIVELY CONNECTED TO SAID MAIN OPERATING MECHANISM, AND HAVING SAID OUTER ENDS CONNECTED TO EACH OTHER BY SAID SPRING SAID SECOND TOGGLE HAVING A KNEE OPERATIVELY CONNECTED TO ONE OF SAID PAIR OF COOPERATING CONTACTS; SID BIASING MEANS BEING ADAPTED TO URGE SAID COOPERRTING CONTACTS INTO FIRM ENGAGEMENT WHEN SAID MAIN OPERATING MECHANISM IS IN SAID FIRST POSITION, AUXILIARY OPERATING MEANS OPERATIVELY CONNECTED INDEPENDENTLY OF SAID MAIN OPERATING MECHANISM TO SAID NE OF SAID PAIR OF COOPERATING CONTACTS; SAID AUXILIARY OPERATING MEANS BEILNG OPERABLE RESPONSIVE TO PRE-DETERMINED FAULT CONDITIONS TO INITIATE OPENING OF SAID PAIR OF COOPERATING CONTACTS BEFORE SAID MAIN OPERATING MECHANISM OPERATES: SAID AUXILIARY OPERATING MEANS BEING OPERATIVELY CONNECTED TO SAID BIASING MEANS AND BEING ADAPTED TO DEFEAT SAID BIASING MEANS INITIALLY DISENGAGEING SAID COOPERATING CONTACTS WHILE SAID MAIN OPERATING MECHANISM REMAINS IN SAID FIRST POSITION AND SAID BIASING MEANS THEREAFTER AIDING SAID AUXILIARY OPERATING MEANS TO DISENGAGE AND HOLD SAID COOPERATING CONTACTS IN DISENGAGED POSITION. 